Pultrusion formation of elongated composite material parts is well known to the art. In essence, pultrusion forms parts by pulling uncured laminations of plies of a matrix material (such as graphite fiber cloth) preimpregnated with an adhesive (such as a thermosetting epoxy) through a die having a desired cross section and hardening the resulting elongated composite material part by curing the adhesive. In order to retain the preimpregnated adhesive within the composite material matrix before the adhesive is cured, the preimpregnated plies are enclosed in one or more slip tapes. The slip tape, along with the preimpregnated composite material plies, is pulled through the pultrusion die, which includes a heated punch, and then into an autoclave, wherein the uncured epoxy is hardened. After the epoxy is cured, the slip tape (which does not adhere to the cured epoxy of the part), can be easily removed.
Prior to the development of the present invention, the tools used to wrap the preimpregnated composite material plies with the slip tape provided, at best, a loose fit of the slip tape on the laminations. The loose fit required the additional use of end stops in the slip tape to aid in containing the liquid epoxy along the slip tape edges during the pultrusion process. The loose fit also made the slip tape and preimpregnated plies difficult to pull through the pultrusion die.
It is therefore desirable to provide a tool and method for tightening the wrap of a slip tape around preimpregnated plies of composite material and preforming the wrapped preimpregnated plies into the shape of the desired elongated part.